<template>
  <div class="pagination">
    <!-- <h1>{{startNumAndEndNum}}--当前的页码{{pageNo}}</h1> -->
    <button :disabled='pageNo == 1' @click="$emit('getPageNo', pageNo-1)">上一页</button>
    <button v-if='startNumAndEndNum.start > 1' @click="$emit('getPageNo', 1)" :class='{active: pageNo == 1}'>1</button>
    <button v-if='startNumAndEndNum.start > 2'>···</button>

    <!-- v-for 遍历数组 从1开始 -->
    <!-- eslint-disable-next-line vue/no-use-v-if-with-v-for -->
    <button v-for= 'page in startNumAndEndNum.end' :key='page.index' v-if='page >= startNumAndEndNum.start' @click="$emit('getPageNo', page)" :class='{active: pageNo == page}'>{{ page }}</button>
    
    <button v-if='startNumAndEndNum.end <= totalPage - 2'>···</button>
    <button v-if='startNumAndEndNum.end < totalPage' @click="$emit('getPageNo', totalPage)" :class='{active: pageNo == totalPage}'>{{totalPage}}</button>
    <button :disabled='pageNo == totalPage' @click="$emit('getPageNo', pageNo+1)">下一页</button>
    
    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
  export default {
    name: "Pagination",
    props: ['pageNo', 'pageSize', 'total', 'continues'],
    computed: {
      totalPage () {
        return Math.ceil (this.total/this.pageSize)
      },
      // 计算连续数字 起始数和结尾数 56789
      startNumAndEndNum () {
        const {continues, pageNo, totalPage} = this
        let start = 0
        let end = 0
        if (continues > totalPage) {
          start = 1
          end = totalPage
        } else {
          start = pageNo - parseInt (continues/2)
          end = pageNo + parseInt (continues/2)
          if (start < 1) {
            start = 1
            end = continues
          }
          if (end > totalPage) {
            end = totalPage
            start = totalPage - continues + 1
          }
        }
        return {start, end}
      }
    }
  }
</script>

<style lang="less" scoped>
  .pagination {
    text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
</style>
